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Answers in red.

June 2010 Chemistry Regents Exam each set of questions is followed by answers and some explanation. Think, write, do, check, then ask. Don’t be lazy, make it real!.

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Answers in red.

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  1. June 2010 Chemistry Regents Exameach set of questions is followed by answers and some explanation. Think, write, do, check, then ask. Don’t be lazy, make it real! 1 The gold foil experiment led to the conclusion that each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil (1) passed through the foil (2) remained trapped in the foil (3) were deflected by the nuclei in gold atoms (4) were deflected by the electrons in gold atoms

  2. Answers in red. 1 The gold foil experiment led to the conclusion that each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil (1) passed through the foil (like it wasn’t even there) (2) remained trapped in the foil (3) were deflected by the nuclei in gold atoms (4) were deflected by the electrons in gold atoms

  3. 2 Which subatomic particles are located in the nucleus of a carbon atom? (1) protons, only (2) neutrons, only (3) protons and neutrons (4) protons and electrons 3 Which part of a helium atom is positively charged? (1) electron (2) neutron (3) nucleus (4) orbital4 The mass of a proton is approximately equal to the mass of (1) an alpha particle (3) a neutron (2) an electron (4) a positron

  4. 2 Which subatomic particles are located in the nucleus of a carbon atom? (1) protons, only (2) neutrons, only (3) protons and neutrons (4) protons and electrons 3 Which part of a helium atom is positively charged? (1) electron (2) neutron (3) nucleus contains protons and neutral neutrons too. (4) orbital4 The mass of a proton is approximately equal to the mass of (1) an alpha particle (3) a neutron - both about 1 AMU (2) an electron (4) a positron

  5. 5 At STP, solid carbon can exist as diamond and graphite. Compared to the molecular structure and chemical properties of diamond, graphite has (1) a different molecular structure and different properties (2) a different molecular structure and the same properties (3) the same molecular structure and different properties (4) the same molecular structure and the same properties 6 Which Group 14 element is classified as a metal? (1) carbon (2) germanium (3) silicon (4) tin 7 The light emitted from a flame is produced when electrons in an excited state (1) absorb energy as they move to lower energy states (2) absorb energy as they move to higher energy states (3) release energy as they move to lower energy states (4) release energy as they move to higher energy states

  6. 5 At STP, solid carbon can exist as diamond and graphite. Compared to the molecular structure and chemical properties of diamond, graphite has (1) a different molecular structure and different properties (2) a different molecular structure and the same properties (differently bonded together, and since you can’t get married with a number 2 pencil which is pure carbon, you have to use a diamond, also pure carbon) (3) the same molecular structure and different properties (4) the same molecular structure and the same properties 6 Which Group 14 element is classified as a metal? (1) carbon (nonmetal) (2) germanium (metalloid) (3) silicon (metalloid) (4) tin (metal) 7 The light emitted from a flame is produced when electrons in an excited state (1) absorb energy as they move to lower energy states (2) absorb energy as they move to higher energy states (3) release energy as they move to lower energy states (the electrons gained energy to go to the higher energy level or orbital, then give back that energy as spectra) (4) release energy as they move to higher energy states

  7. 8 An atom of which element has the greatest attraction for electrons in a chemical bond? (1) As (2) Ga (3) Ge (4) Se 9 Which formula represents a polar molecule? (1) H2 (2) H2O (3) CO2 (4) CCl4 10 Two categories of compounds are (1) covalent and molecular (2) covalent and metallic (3) ionic and molecular (4) ionic and metallic

  8. 8 An atom of which element has the greatest attraction for electrons in a chemical bond?This means highest electronegativity value, look at table S! (1) As 2.2 (2) Ga 1.8 (3) Ge 2.0 (4) Se 2.6 9 Which formula represents a polar molecule? This means no radial symmetry! (1) H2(2) H2O classic polar molecule (3) CO2 (4) CCl4 10 Two categories of compounds are (1) covalent and molecular (2) covalent and metallic (3) ionic and molecular – formed by ions attracting each other, or by covalent bonds (4) ionic and metallic metals are atoms bonded together, or alloys which are melted together. They are not compounds!

  9. 11 Which type of bond is found between atoms of solid cobalt? (1) nonpolar covalent (2) polar covalent (3) metallic (4) ionic 12 Which equation represents sublimation? (1) I2(s) → I2(G)(2) I2(S) →I2(L) (3) I2(L) → I2(G)(4) I2(L) →I2(S) 13 Which sample of ethanol has particles with the highest average kinetic energy? (1) 10.0 mL of ethanol at 25°C (2) 10.0 mL of ethanol at 55°C (3) 100.0 mL of ethanol at 35°C (4) 100.0 mL of ethanol at 45°C

  10. 11 Which type of bond is found between atoms of solid cobalt? (1) nonpolar covalent (2) polar covalent (3) metallic (4) ioniccobalt is a metal, the atoms are held together by metallic bonds which have packed cations with a sea of loose valence electrons 12 Which equation represents sublimation? This means solid to gas transition (1) I2(S) → I2(G)(2) I2(S) →I2(L) (3) I2(L) → I2(G)(4) I2 (L) →I2(S) 13 Which sample of ethanol has particles with the highest average kinetic energy? (1) 10.0 mL of ethanol at 25°C (2) 10.0 mL of ethanol at 55°C kinetic energy and temperature are like Michael Jackson’s hand and his shiny glove. Mass is not relevant in averages. (3) 100.0 mL of ethanol at 35°C (4) 100.0 mL of ethanol at 45°C

  11. 14 The molarity of an aqueous solution of NaCl is defined as the (1) grams of NaCl per liter of water (2) grams of NaCl per liter of solution (3) moles of NaCl per liter of water (4) moles of NaCl per liter of solution 15 A real gas behaves least like an ideal gas under the conditions of (1) low temperature and low pressure (2) low temperature and high pressure (3) high temperature and low pressure (4) high temperature and high pressure 16 Which sample of matter can be separated into different substances by physical means? (1) LiCl(AQ) (2) LiCl(S) (3) NH3(G) (4) NH(L)

  12. 14 The molarity of an aqueous solution of NaCl is defined as the (1) grams of NaCl per liter of water (2) grams of NaCl per liter of solution (3) moles of NaCl per liter of water just look at the formula on table T! (4) moles of NaCl per liter of solution 15 A real gas behaves least like an ideal gas under the conditions of (1) low temperature and low pressure (2) low temperature and high pressure - this is a backwards question, most annoying. Low temperature means slow moving particles that will have lots of collisions and chances to connect. High pressure also increases the likelihood of particles combining. (3) high temperature and low pressure (4) high temperature and high pressure 16 Which sample of matter can be separated into different substances by physical means? (1) LiCl(AQ) (2) LiCl(S) (3) NH3(G) (4) NH(L)only #1 is a mixture, lithium chloride and water. #2 is a compound, so is #3 and #4. Compounds can only be separated by chemical means, but by taking advantage of differences in PHYSICAL properties mixtures can be taken apart.

  13. 17 At STP, 1.0 liter of helium contains the same total number of atoms as • 1.0 L of Ne (2) 2.0 L of Kr (3) 0.5 L of Rn (4) 1.5 L of Ar • 18 Which statement describes the particles of an ideal gas? • (1) The particles move in well-defined, circular paths. • (2) When the particles collide, energy is lost. • (3) There are forces of attraction between the particles. • (4) The volume of the particles is negligible. • 19 A chemical reaction between iron atoms & oxygen molecules can only occur if • (1) the particles are heated • (2) the atmospheric pressure decreases • (3) there is a catalyst present • (4) there are effective collisions between the particles

  14. 17 At STP, 1.0 liter of helium contains the same total number of atoms as • 1.0 L of Ne (2) 2.0 L of Kr (3) 0.5 L of Rn (4) 1.5 L of ArAvogadro’s Hypothesis, equal volumes of different gases at the same temperature and pressure have the same numbers of particles (or the same number of moles of particles) • 18 Which statement describes the particles of an ideal gas? • (1) The particles move in well-defined, circular paths. – no, straight lines • (2) When the particles collide, energy is lost. – no loss of energy for ideal gases, just real ones! • (3) There are forces of attraction between the particles. – no, not for idea gases, • (4) The volume of the particles is negligible. – yes, the particle size is insignificant as compared to the volume the gas takes up. This is obvious when we chill a gas to a liquid, it’s so much smaller! • 19 A chemical reaction between iron atoms & oxygen molecules can only occur if • (1) the particles are heated • (2) the atmospheric pressure decreases • (3) there is a catalyst present • (4) there are effective collisions between the particles REACTIONS only occur when proper collisions occur. The Kinetic Molecular theory states this.

  15. 20 Given the equation representing a phase change at equilibrium: H2O(S) H2O(L) • Which statement describes this equilibrium? • (1) The H2O(S) melts faster than the H2O(L) freezes. • (2) The H2O(L) freezes faster than the H2O(S)melts. • (3) The mass of H2O(S) must equal the mass of H2O(L). • (4) The mass of H2O(L) and the mass of H2O(S)each remain constant. • 21 A molecule of an organic compound contains at least one atom of • carbon (2) chlorine (3) nitrogen (4) oxygen • 22 In a chemical reaction, the difference between the potential energy of the products and the potential energy of the reactants is equal to the • (1) activation energy • (2) entropy of the system • (3) heat of fusion • (4) heat of reaction

  16. 20 Given the equation representing a phase change at equilibrium: H2O(S) H2O(L) • Which statement describes this equilibrium? • (1) The H2O(S) melts faster than the H2O(L) freezes. • (2) The H2O(L) freezes faster than the H2O(S) melts. • (3) The mass of H2O(S) must equal the mass of H2O(L). • (4) The mass of H2O(L) and the mass of H2O(S) each remain constant. This is oddly stated, but since it’s in a dynamic equilibrium, where the forward reaction rate equals the reverse, what ever the mass on each side is, it will remain the same. If you started with 100g of ice and only 25 g of water, the masses would remain the same, not necessarily be equal. • 21 A molecule of an organic compound contains at least one atom of • carbon (2) chlorine (3) nitrogen (4) oxygenThe first word in an organic chem textbook is carbon. It’s central to all organic molecules. • 22 In a chemical reaction, the difference between the potential energy of the products and the potential energy of the reactants is equal to the • (1) activation energy • (2) entropy of the system • (3) heat of fusion • (4) heat of reaction – look at table I now, the heat of reaction means ΔH!

  17. 23 A carbon-carbon triple bond is found in a molecule of • butane (2) butanone (3) butene (4) butyne • 24 Which statement describes one characteristic of an operating electrolytic cell? • (1) It produces electrical energy. • (2) It requires an external energy source. • (3) It uses radioactive nuclides. • (4) It undergoes a spontaneous redox reaction. • 25 Which compound when dissolved in water is an Arrhenius acid? • (1) CH3OH (2) HCl (3) NaCl (4) NaOH

  18. 23 A carbon-carbon triple bond is found in a molecule of (1) butane (2) butanone (3) butene (4) butyne this is the only alkyne, look at table Q to know alkynes have a triple bond 24 Which statement describes one characteristic of an operating electrolytic cell? (1) It produces electrical energy. (2) It requires an external energy source. - electricity to force a non-spontaneous redox (3) It uses radioactive nuclides. (4) It undergoes a spontaneous redox reaction. 25 Which compound when dissolved in water is an Arrhenius acid? (1) CH3OH (2) HCl (3) NaCl (4) NaOHYou could of course look at Table K, the acids and see that it’s the only acid listed, or remember that Svante Arrhenius said solutions with hydrogen ions (or those hydroniums) in excess. #1 is methanol, an alcohol, #3 is salty water, and #4 is an Arrhenius base

  19. 26 An acid can be defined as an • (1) H+ acceptor (2) H+ donor (3) OH− acceptor (4) OH− donor • 27 Which nuclear emission has no charge and no mass? • (1) alpha particle (2) beta particle (3) gamma ray (4) positron • 28 During which process can 10.0 milliliters of a 0.05 M HCl(aq) solution be used to determine the unknown concentration of a given volume of NaOH(aq) solution? • evaporation (2) distillation (3) filtration (4) titration • 29 Which radioisotope is matched with its decay mode? • (1) H-3 and γ (2) K-42 and β+ (3) N-16 and α (4) P-32 and β− • 30 Which reaction is accompanied by the release of the greatest amount of energy? • (1) combustion of 10. g of propane (2) electrolysis of 10. g of water • (3) nuclear fission of 10. g of uranium (4) oxidation of 10. g of iron

  20. 26 An acid can be defined as an • (1) H+ acceptor (2) H+ donor(3) OH− acceptor (4) OH− donoranother backwards question, NH3 is a base because of this theory, and that makes the water which donates the hydrogen ion an acid. • 27 Which nuclear emission has no charge and no mass? • alpha particle (2) beta particle (3) gamma ray (4) positronJust look at Table O, the masses and charges are all listed. • 28 During which process can 10.0 milliliters of a 0.05 M HCl(aq) solution be used to determine the unknown concentration of a given volume of NaOH(aq) solution? • evaporation (2) distillation (3) filtration (4) titration – you did this in lab • 29 Which radioisotope is matched with its decay mode? • (1) H-3 and γ (2) K-42 and β+ (3) N-16 and α (4) P-32 and β−You could just guess if you’re lazy and hope for the best, or just look at table N • 30 Which reaction is accompanied by the release of the greatest amount of energy? • (1) combustion of 10. g of propane (2) electrolysis of 10. g of water • (3) nuclear fission of 10. g of uranium (4) oxidation of 10. g of ironfission happens in nuclear bombs or in nuclear reactors

  21. 31 The total number of protons, electrons, and neutrons in each of four different atoms are shown in the table below. Which two atoms are isotopes of the same element? (1) A and D (3) X and D (2) A and Z (4) X and Z

  22. 31 The total number of protons, electrons, and neutrons in each of four different atoms are shown in the table below. Which two atoms are isotopes of the same element?Isotopes are chemically identical atoms (same protons and electrons) with different masses (different neutrons) (1) A and D (3) X and D (2) A and Z (4) X and Z

  23. 32 Which Lewis electron-dot diagram represents an atom in the ground state for a Group 13 element? 33 Which element forms a compound with chlorine with the general formula MCl? (1) Rb (2) Ra (3) Re (4) Rn

  24. 32 Which Lewis electron-dot diagram represents an atom in the ground state for a Group 13 element? Boron is in group 13, choose an element in the group, don’t pick some unknown one. Boron has 5 electrons, but a 2.3 configuration, only 3 electrons in the drawing. 33 Which element forms a compound with chlorine with the general formula MCl?This is a one to one ratio of cations to anions. Cl makes a -1 anion, so let’s find a +1 cation here (from group 1) (1) Rb (2) Ra (3) Re (4) Rn

  25. 34 A sample of an element has a mass of 34.261 grams and a volume of 3.8 cubic centimeters. To which number of significant figures should the calculated density of the sample be expressed? (1) 5 (2) 2 (3) 3 (4) 4 35 Which characteristics both generally decrease when the elements in Period 3 on the Periodic Table are considered in order from left to right? (1) nonmetallic properties and atomic radius (2) nonmetallic properties and ionization energy (3) metallic properties and atomic radius (4) metallic properties and ionization energy 36 Which formula is both a molecular and an empirical formula? (1) C6H12O6 (2) C2H4O2 (3) C3H8O (4) C4H8

  26. 34 A sample of an element has a mass of 34.261 grams and a volume of 3.8 cubic centimeters. To which number of significant figures should the calculated density of the sample be expressed? (1) 5 (2) 2 (3) 3 (4) 4answers get the least number of SF from the math, the 3.8 has 2 SF 35 Which characteristics both generally decrease when the elements in Period 3 on the Periodic Table are considered in order from left to right? (1) nonmetallic properties and atomic radius (2) nonmetallic properties and ionization energy (3) metallic properties and atomic radius – going across the table you always get smaller atoms (check table S for radius size) and you go from metals to metalloids, to non metals, to noble gases (much less metallic). (4) metallic properties and ionization energy 36 Which formula is both a molecular and an empirical formula? (1) C6H12O6 (2) C2H4O2(3) C3H8O (4) C4H8Molecular formulas are the formulas of the compounds. Empirical formulas are the lowest ratios of atoms to atoms in a compound. Sometimes they are the same, as in CO2 and this one. #3 is the only formula that can’t be reduced.

  27. 37 An atom of argon in the ground state tends not to bond with an atom of a different element because the argon atom has (1) more protons than neutrons (2) more neutrons than protons (3) a total of two valence electrons (4) a total of eight valence electrons 38 Which formula represents a molecule having a nonpolar covalent bond? 1 2 3 4

  28. 37 An atom of argon in the ground state tends not to bond with an atom of a different element because the argon atom has (1) more protons than neutrons (2) more neutrons than protons (3) a total of two valence electrons (4) a total of eight valence electrons – full orbitals means noble gas, means that it most likely will never bond with anything else. 38 Which formula represents a molecule having a nonpolar covalent bond? 1 2 3 4 Only #3 has a C-C bond which is nonpolar (same electronegativity values). All other bonds are atoms with different electronegativity values.

  29. 39 Which compound has the lowest vapor pressure at 50°C? • ethanoic acid (2) ethanol (3) propanone (4) water • 40 Given the potential energy diagram and equation representing the reaction between substances A and D: G Potential energy A + D Reaction coordinate A + D G According to Table I, substance G could be (1) HI(G) (2) H2O(G) (3) CO2(G) (4) C2H6(G)

  30. 39 Which compound has the lowest vapor pressure at 50°C? Check Table H • ethanoic acid (2) ethanol (3) propanone (4) water • 40 Given the potential energy diagram and equation representing the reaction between substances A and D: G Potential energy A + D Reaction coordinate A + D G According to Table I, substance G could be (1) HI(G)(2) H2O(G) (3) CO2(G) (4) C2H6(G) This is endothermic, ΔH has to be positive, so, if G = HI gas, the ΔH for that is +53.0 kJ/mole

  31. 41 A sample of gas confined in a cylinder with a movable piston is kept at constant pressure. The volume of the gas doubles when the temperature of the gas is changed from (1) 400. K to 200. K (3) 400.°C to 200.°C (2) 200. K to 400. K (4) 200.°C to 400.°C 42 According to Table F, which compound is soluble in water? (1) barium phosphate (3) silver iodide (2) calcium sulfate (4) sodium perchlorate 43 Given the equation representing a system at equilibrium: N2(G)+ 3H2(G) 2NH3(G)+ energy Which changes occur when the temperature of this system is decreased? (1) The concentration of H2(G) increases + the concentration of N2(G) increases. (2) The concentration of H2(G) decreases + the concentration of N2(G) increases. (3) The concentration of H2(G) decreases + the concentration of NH3(G) decreases. (4) The concentration of H2(G) decreases + the concentration of NH3(G) increases.

  32. 41 A sample of gas confined in a cylinder with a movable piston is kept at constant pressure. The volume of the gas doubles when the temperature of the gas is changed from (1) 400. K to 200. K (3) 400.°C to 200.°C (2) 200. K to 400. K (4) 200.°C to 400.°C 42 According to Table F, which compound is soluble in water? Look it up! (1) barium phosphate (3) silver iodide (2) calcium sulfate (4) sodium perchlorate 43 Given the equation representing a system at equilibrium: N2(G)+ 3H2(G) 2NH3(G)+ energy Which changes occur when the temperature of this system is decreased? Energy is removed! Forward reaction is favored! (1) The concentration of H2(G) increases + the concentration of N2(G) increases. (2) The concentration of H2(G) decreases + the concentration of N2(G) increases. (3) The concentration of H2(G) decreases + the concentration of NH3(G) decreases. (4) The concentration of H2(G) decreases + the concentration of NH3(G) increases. V1T1 V2T2 22.4 L200 K X 400 K = = Do some math to try them all, but use Kelvin, not centigrade! That’s an example.

  33. 44 Which formula represents an unsaturated hydrocarbon?

  34. 44 Which formula represents an unsaturated hydrocarbon? This is not a hydrocarbon, this is ethanal, an aldehyde This is propane, it is a saturated hydrocarbon. This is propene, an unsaturated hydrocarbon. Not a hydrocarbon, this is an ether.

  35. 45 Which half-reaction equation represents the reduction of an iron(II) ion? (1) Fe2+ → Fe3+ + e− (3) Fe3+ + e − → Fe2+ (2) Fe2+ + 2e− → Fe (4) Fe → Fe2+ + 2e− 46 Which metal is more active than H2? (1) Ag (2) Au (3) Cu (4) Pb 47 Given the balanced ionic equation representing the reaction in an operating voltaic cell: Zn(S) + Cu2+(AQ)→ Zn2+(AQ) + Cu(S) The flow of electrons through the external circuit in this cell is from the (1) Cu anode to the Zn cathode (2) Cu cathode to the Zn anode (3) Zn anode to the Cu cathode (4) Zn cathode to the Cu anode

  36. 45 Which half-reaction equation represents the reduction of an iron(II) ion?Reduction is the gain of electrons, Iron (II) is the +2 cation, so… (1) Fe2+ → Fe3+ + e− (3) Fe3+ + e − → Fe2+ (2) Fe2+ + 2e− → Fe (4) Fe → Fe2+ + 2e− 46 Which metal is more active than H2? (1) Ag (2) Au (3) Cu (4) Pb for this one, look at table J, which is “higher” on the list than hydrogen? 47 Given the balanced ionic equation representing the reaction in an operating voltaic cell: Zn(S) + Cu2+(AQ)→ Zn2+(AQ) + Cu(S) The flow of electrons through the external circuit in this cell is from the (1) Cu anode to the Zn cathode (2) Cu cathode to the Zn anode (3) Zn anode to the Cu cathode (4) Zn cathode to the Cu anode Zinc is “higher” than copper, it will oxidize. Zinc has to be the anode. Copper will have to be reduced, it has to be the cathode. If you don’t “see” this, draw out a voltaic cell (for the last time of your life) and figure it all out!

  37. 48 Which laboratory test result can be used to determine if KCl (S) is an electrolyte? • (1) pH of KCl(AQ) (2) pH of KCl (S) • (3) electrical conductivity of KCl (AQ) (4) electrical conductivity of KCl (S) • 49 Which compound is produced when HCl (AQ) is neutralized by Ca(OH)2 (AQ) ? • CaCl2 (2) CaH2 (3) HClO (4) HClO2 • 50 Which nuclides are used to date the remains of a once-living organism? • (1) C-14 and C-12 (3) I-131 and Xe-131 • (2) Co-60 and Co-59 (4) U-238 and Pb-206

  38. 48 Which laboratory test result can be used to determine if KCl (S) is an electrolyte? • (1) pH of KCl(AQ) (2) pH of KCl (S) • (3) electrical conductivity of KCl (AQ) (4) electrical conductivity of KCl (S) An electrolyte will conduct electricity if put into water, or if already in water. Acid base level is not important, and this has a pH of 7 anyway. The electrical conduction of a solid ionic compound is zero. It has to be three. • 49 Which compound is produced when HCl (AQ) is neutralized by Ca(OH)2 (AQ) ? • CaCl2 (2) CaH2 (3) HClO (4) HClO2 You should write out the balanced chemical reaction for this acid base neutralization. Water will be one product, here the other will be calcium chloride(AQ) • 50 Which nuclides are used to date the remains of a once-living organism? • C-14 and C-12 (2) Co-60 and Co-59(3) I-131 and Xe-131 (4) U-238 and Pb-206 • It’s the ratio of radioactive carbon-14 as compared the amount of “normal” stable carbon that allows to carbon date formerly living things. It won’t work past about 80,000 years, because the half life is so short (5730 years) after 80,000 years, the measuring is too hard.

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